U.S. patent number 10,189,273 [Application Number 15/464,882] was granted by the patent office on 2019-01-29 for head unit having nozzle chips arranged side by side and liquid jetting apparatus including the same.
This patent grant is currently assigned to BROTHER KOGYO KABUSHIKI KAISHA. The grantee listed for this patent is BROTHER KOGYO KABUSHIKI KAISHA. Invention is credited to Hideki Hayashi, Taisuke Mizuno, Keita Sugiura.
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United States Patent |
10,189,273 |
Hayashi , et al. |
January 29, 2019 |
Head unit having nozzle chips arranged side by side and liquid
jetting apparatus including the same
Abstract
A head unit includes: nozzle chips which are arranged side by
side in a first direction, each of the nozzle chips having a
jetting surface and nozzles aligned in a predetermined direction
parallel to the jetting surface and crossing both of the first
direction and a second direction orthogonal to the first direction;
a holder configured to hold the nozzle chips from a side opposite
to the jetting surface; and a fixing plate to which the nozzle
chips are fixed and which is arranged on a side facing the jetting
surface of each of the nozzle chips, wherein the holder has first
walls arranged in the second direction so as to sandwich the nozzle
chips therebetween; each of the first walls has first projections
formed on an end surface thereof facing the fixing plate; and the
first projections make contact with the fixing plate.
Inventors: |
Hayashi; Hideki (Nagoya,
JP), Sugiura; Keita (Toyoake, JP), Mizuno;
Taisuke (Yokkaichi, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
BROTHER KOGYO KABUSHIKI KAISHA |
Nagoya-shi, Aichi-ken |
N/A |
JP |
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Assignee: |
BROTHER KOGYO KABUSHIKI KAISHA
(Nagoya-Shi, Aichi-Ken, JP)
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Family
ID: |
59959087 |
Appl.
No.: |
15/464,882 |
Filed: |
March 21, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170282553 A1 |
Oct 5, 2017 |
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Foreign Application Priority Data
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Mar 31, 2016 [JP] |
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2016-070943 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B41J
2/2146 (20130101); B41J 2/145 (20130101); B41J
2202/19 (20130101); B41J 2202/20 (20130101) |
Current International
Class: |
B41J
2/21 (20060101); B41J 2/145 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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104691109 |
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Jun 2015 |
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CN |
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2015-110305 |
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Jun 2015 |
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JP |
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2015-120292 |
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Jul 2015 |
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JP |
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Other References
Chinese Official Action dated Aug. 1, 2018 received in related
application CN 201710164766.7, together with an English language
translation. cited by applicant.
|
Primary Examiner: Legesse; Henok
Attorney, Agent or Firm: Scully, Scott, Murphy &
Presser, P.C.
Claims
What is claimed is:
1. A head unit comprising: nozzle chips which are arranged side by
side in a first direction, each of the nozzle chips having a
jetting surface and nozzles aligned in a predetermined direction
parallel to the jetting surface and crossing both of the first
direction and a second direction orthogonal to the first direction;
a holder configured to hold the nozzle chips from a side opposite
to the jetting surface of each of the nozzle chips; and a fixing
plate to which the nozzle chips are fixed and which is arranged on
a side facing the jetting surface of each of the nozzle chips,
wherein the holder has first walls arranged in the second direction
so as to sandwich the nozzle chips therebetween, each of the first
walls has first projections formed on a lower surface thereof
facing the fixing plate, and the first projections make contact
with the fixing plate and wherein two nozzle chips included in the
nozzle chips are exposed from the holder in the first
direction.
2. The head unit according to claim 1, wherein end surfaces of end
portions, of each of the nozzle chips, in the predetermined
direction cross the first direction, and a portion of each of the
first walls is arranged to be interposed between the end portions
of two adjacent nozzle chips, among the nozzle chips, which are
adjacent in the first direction.
3. The head unit according to claim 2, wherein the first
projections are provided as two or more first projections which are
arranged along the end surfaces of the end portions, of each of the
nozzle chips, in the predetermined direction.
4. The head unit according to claim 1, wherein the first
projections arranged on one side in the second direction with
respect to the nozzle chips and the first projections arranged on
the other side in the second direction with respect to the nozzle
chips are arranged to face one another in the predetermined
direction with the nozzle chips sandwiched therebetween.
5. The head unit according to claim 1, wherein the nozzles of each
of the nozzle chips include first nozzles arranged on one side in
the predetermined direction and second nozzles arranged on the
other side in the predetermined direction, the first nozzles and
the second nozzles being configured to jet different kinds of
liquids, respectively, and no wall of the holder is arranged
between two nozzle chips, among the nozzle chips, which are
adjacent in the first direction.
6. The head unit according to claim 1, wherein the nozzle chips
include a first nozzle chip and a second nozzle chip which are
adjacent in the first direction, and a part of the nozzles
belonging to the first nozzle chip and a part of the nozzles
belonging to the second nozzle chip are overlapped with each other
in the second direction.
7. The head unit according to claim 1, wherein the holder further
includes third walls which are arranged on outer sides in the first
direction with respect to the nozzle chips.
8. A head unit comprising: nozzle chips which are arranged side by
side in a first direction, each of the nozzle chips having a
jetting surface and nozzles aligned in a predetermined direction
parallel to the jetting surface and crossing both of the first
direction and a second direction orthogonal to the first direction;
a holder configured to hold the nozzle chips from a side opposite
to the jetting surface of each of the nozzle chips; and a fixing
plate to which the nozzle chips are fixed and which is arranged on
a side facing the jetting surface of each of the nozzle chips,
wherein the holder has first walls arranged in the second direction
so as to sandwich the nozzle chips therebetween, each of the first
walls has first projections formed on a lower surface thereof
facing the fixing plate, and the first projections make contact
with the fixing plate, wherein two nozzle chips included in the
nozzle chips are exposed from the holder in the first direction,
wherein end surfaces of end portions, of each of the nozzle chips,
in the predetermined direction cross the first direction, and a
portion of each of the first walls is arranged to be interposed
between the end portions of two adjacent nozzle chips, among the
nozzle chips, which are adjacent in the first direction, and
wherein at least a portion of each of the first projections is
arranged in the portion, of one of the first walls, which is
interposed between the two adjacent nozzle chips.
9. The head unit according to claim 8, wherein the end surfaces of
the end portions, of each of the nozzle chips, in the predetermined
direction are parallel to a direction orthogonal to the
predetermined direction.
10. A head unit comprising: nozzle chips which are arranged side by
side in a first direction, each of the nozzle chips having a
jetting surface and nozzles aligned in a predetermined direction
parallel to the jetting surface and crossing both of the first
direction and a second direction orthogonal to the first direction;
a holder configured to hold the nozzle chips from a side opposite
to the jetting surface of each of the nozzle chips; and a fixing
plate to which the nozzle chips are fixed and which is arranged on
a side facing the jetting surface of each of the nozzle chips,
wherein the holder has first walls arranged in the second direction
so as to sandwich the nozzle chips therebetween, each of the first
walls has first projections formed on a lower surface thereof
facing the fixing plate, and the first projections make contact
with the fixing plate, wherein two nozzle chips included in the
nozzle chips are exposed from the holder in the first direction,
wherein the holder has a second wall which extends in the
predetermined direction and which is arranged between two adjacent
nozzle chips, among the nozzle chips, which are adjacent in the
first direction, and an end surface, of the second wall, on a side
facing the fixing plate, is formed with second projections which
make contact with the fixing plate.
11. The head unit according to claim 10, wherein a size of each of
the first projections is greater than a size of each of the second
projections.
12. The head unit according to claim 10, wherein the nozzle chips
are provided as at least four nozzle chips, the second wall is
provided as second walls, and the second walls include two second
walls each of which is arranged between the two adjacent nozzle
chips, which are located closer to one end side or the other end
side in the first direction.
13. The head unit according to claim 12, wherein the second walls
also include a second wall arranged between the two adjacent nozzle
chips which is located on a central side in the first
direction.
14. The head unit according to claim 13, wherein in each of the
second walls arranged between the two adjacent nozzle chips located
closer to the one end side or the other end side, the size of each
of the second projections is greater than the size of each of the
second projections in the second wall arranged between the two
adjacent nozzle chips located on the central side.
15. The head unit according to claim 13, wherein in each of the
second walls arranged between the two adjacent nozzle chips located
closer to the one end side or the other end side, arrangement pitch
of the second projections in the predetermined direction is smaller
than arrangement pitch of the second projections in the
predetermined direction in the second wall arranged between the two
adjacent nozzle chips arranged on the central side.
16. The head unit according to claim 10, wherein the second wall is
provided as second walls which are arranged at all locations
between the nozzle chips.
17. The head unit according to claim 10, wherein the second wall is
provided as second walls arranged only at a portion of locations
between the nozzle chips.
18. The head unit according to claim 10, wherein the second
projections are formed at least in a central portion, of the second
wall, in the predetermined direction.
19. The head unit according to claim 10, wherein the second wall is
provided as two second walls arranged respectively at both sides,
of one of the nozzle chips, in the first direction, and the second
projections of one of the two second walls and the second
projections of the other of the two second walls are arranged to
face one another in a direction parallel to the jetting surface and
orthogonal to the predetermined direction, with the one of the
nozzle chips sandwiched therebetween.
20. The head unit according to claim 10, wherein the nozzle chips
jet a same kind of liquid from the nozzles.
21. A liquid jetting apparatus comprising head units arranged side
by side in a first direction, each of the head units including:
nozzle chips which are arranged side by side in the first
direction, each of the nozzle chips having a jetting surface and
nozzles aligned in a predetermined direction parallel to the
jetting surface and crossing both of the first direction and a
second direction orthogonal to the first direction; a holder
configured to hold the nozzle chips from a side opposite to the
jetting surface of each of the nozzle chips; and a fixing plate to
which the nozzle chips are fixed and which is arranged on a side
facing the jetting surface of each of the nozzle chips, wherein the
holder has first walls arranged in the second direction so as to
sandwich the nozzle chips therebetween; two nozzle chips included
in the nozzle chips are exposed from the holder in the first
direction; each of the first walls has first projections formed on
a lower surface thereof facing the fixing plate; and the first
projections make contact with the fixing plate and wherein two
nozzle chips included in the nozzle chips are exposed from the
holder in the first direction.
Description
CROSS REFERENCE TO RELATED APPLICATION
The present application claims priority from Japanese Patent
Application No. 2016-070943 filed on Mar. 31, 2016 the disclosure
of which is incorporated herein by reference in its entirety.
BACKGROUND
Field of the Invention
The present invention relates to a head unit, and a liquid jetting
apparatus provided with a plurality of head units.
Description of the Related Art
Conventionally, there is known a line-type jetting head, as the
liquid jetting apparatus, having a configuration wherein a
plurality of head units (ink-jet recording heads) are arranged side
by side in the width direction of a recording medium.
In such a line-type jetting head, each of the head units has a
plurality of nozzle chips (head bodies) which are arranged side by
side in the width direction of the recording medium, a holding
member holding the plurality of nozzle chips, and a fixing plate
arranged on a side of jetting surfaces of the plurality of nozzle
chips.
A plurality of nozzles of each of the nozzle chips are aligned in
an oblique direction crossing each of the width direction of the
recording medium and a conveyance direction in which the recording
medium is conveyed. The upper surfaces of the plurality of nozzle
chips are joined to the back surface of the holding member with an
adhesive. In this line-type jetting head, the variation
(unevenness) in heights of the jetting surfaces among the plurality
of nozzle chips is absorbed by the adhesive between the nozzle
chips and the holding member.
On the other hand, there is also known a line-type jetting head
having such a configuration that the positions of a plurality of
head units are alternately shifted in the conveyance direction of
the recording medium (a so-called staggered arrangement), and which
also has a common fixing plate arranged on a side facing the
jetting surfaces of the plurality of head units, and a case member
arranged on a side opposite to the fixing plate with respect to the
plurality of head units.
The case member has walls arranged to surround the head units,
respectively, and a plurality of projections (projecting portions)
are formed on each of the walls at an end surface thereof on the
side facing the fixing plate. By pressing the plurality of
projections against the fixing plate, the fixing plate is made to
follow the positions of end portions of the plurality of
projections. With this, the flatness of the fixing plate is
enhanced, thereby suppressing any variation in the heights of the
jetting surfaces among the plurality of head units.
SUMMARY
In the former line-type jetting head, any variation in the heights
of the jetting surfaces among the plurality of nozzle chips is
absorbed by the adhesive. In reality, however, it is difficult to
suppress the above-described variation to be small only with the
adhesive.
On the other hand, in the latter line-type jetting head, an attempt
is made to flatten the fixing plate by pressing, against the fixing
plate, the plurality of projections which are formed in the case
member and arranged so as to surround the respective head units.
However, in a case that an attempt is made to apply the technique
of the latter line-type jetting head to the configuration of the
former line-type jetting head, the following problem might
occur.
In the former line-type jetting head, the nozzles are aligned in
rows in the oblique direction crossing both of the conveyance
direction and the width direction of the recording medium. In this
configuration, it is desired that the distance between the nozzle
chips which belong respectively to two head units, included in the
plurality of head units, and which are adjacent in the width
direction is decreased as little as possible, from the viewpoint of
arranging nozzles belonging to the two adjacent head units
respectively at an equal spacing distance with respect to the width
direction, or from the viewpoint of partially overlapping the
positions in the width direction of the nozzles belonging to one of
the two adjacent head units respectively with the positions in the
width direction of the nozzles belonging to the other of the two
adjacent head units.
However, as in the configuration of the latter line-type jetting
head wherein each of the walls is present to surround one of the
head units, the walls are arranged with respect to one of the head
units, at both outsides in the width direction of the recording
medium. Accordingly, in a case that the configuration of the latter
line-type jetting head is applied as it is to the former line-type
jetting head, the walls are consequently arranged between the
adjacent two head units. Accordingly, this increases the distance
between the nozzle chips which belong to the two adjacent head
units, respectively, and which are adjacent to each other.
The present teaching has been made in view of the above-described
situation, and object of the present teaching is to suppress any
variation in heights in the jetting surfaces of the plurality of
nozzle chips in an assured manner, without increasing the distance
between the nozzle chips which belong to the adjacent head units,
respectively, and which are adjacent to each other.
According to a first aspect of the present teaching, there is
provided a head unit including:
nozzle chips which are arranged side by side in a first direction,
each of the nozzle chips having a jetting surface and nozzles
aligned in a predetermined direction parallel to the jetting
surface and crossing both of the first direction and a second
direction orthogonal to the first direction;
a holder configured to hold the nozzle chips from a side opposite
to the jetting surface of each of the nozzle chips; and
a fixing plate to which the nozzle chips are fixed and which is
arranged on a side facing the jetting surface of each of the nozzle
chips,
wherein the holder has first walls arranged in the second direction
so as to sandwich the nozzle chips therebetween,
each of the first walls has first projections formed on an end
surface thereof facing the fixing plate, and
the first projections make contact with the fixing plate.
In the head unit according to the first aspect of the present
teaching, two nozzle chips included in the nozzle chips may be
exposed from the holder in the first direction.
According to a second aspect of the present teaching, there is
provided a liquid jetting apparatus including head units arranged
side by side in a first direction, each of the head units
including:
nozzle chips which are arranged side by side in the first
direction, each of the nozzle chips having a jetting surface and
nozzles aligned in a predetermined direction parallel to the
jetting surface and crossing both of the first direction and a
second direction orthogonal to the first direction;
a holder configured to hold the nozzle chips from a side opposite
to the jetting surface of each of the nozzle chips; and
a fixing plate to which the nozzle chips are fixed and which is
arranged on a side facing the jetting surface of each of the nozzle
chips,
wherein the holder has first walls arranged in the second direction
so as to sandwich the nozzle chips therebetween;
two nozzle chips included in the nozzle chips are exposed from the
holder in the first direction;
each of the first walls has first projections formed on an end
surface thereof facing the fixing plate; and
the first projections make contact with the fixing plate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic plane view of a printer according to an
embodiment of the present teaching.
FIG. 2 is a plane view of an ink-jet head.
FIG. 3 is an exploded perspective view of a head unit.
FIG. 4 is a top view of the head unit.
FIG. 5 is a bottom view of the head unit in a state that a fixing
plate is removed.
FIG. 6A is a cross-sectional view taken along a line VIA-VIA in
FIG. 4, and FIG. 6B is a cross-sectional view taken along a line
VIB-VIB in FIG. 4.
FIG. 7 is a bottom view of a head unit of a modification 1.
FIG. 8 is a bottom view of a head unit of a modification 2.
FIG. 9 is a bottom view of a head unit of a modification 3.
FIGS. 10A and 10B are each a bottom view of a head unit of a
modification 4.
FIG. 11 is a bottom view of a head unit of a modification 5.
FIGS. 12A and 12B are each a bottom view of a head unit of a
modification 6.
FIGS. 13A to 13C are each a bottom view of a head unit of a
modification 7.
FIG. 14 is a bottom view of a head unit of a modification 8.
FIG. 15 is a bottom view of a head unit of a modification 9.
FIG. 16 is a bottom view of a modification of the head unit
depicted in FIG. 15.
FIG. 17 is a bottom view of another modification of the head unit
depicted in FIG. 5.
FIG. 18 is a top view of a head unit of a modification 10.
FIG. 19 is a cross-sectional view of a modification 11,
corresponding to FIG. 6B.
DESCRIPTION OF THE EMBODIMENTS
Next, an embodiment of the present teaching will be explained, with
reference to the drawings as appropriate. Note that in the
following explanation, a conveyance direction in which a recording
paper (recording sheet) 100 is conveyed is defined as the
front/rear direction of a printer 1. Further, the width direction
of the recording paper 100 (paper-width direction or sheet-width
direction) is defined as the left/right direction of the printer 1.
Furthermore, a direction perpendicular to the sheet surface of FIG.
1 and orthogonal to the front/rear direction and the left/right
direction is defined as the up/down direction of the printer 1.
<Schematic Configuration of Printer>
As depicted in FIG. 1, the printer 1 is provided with a casing 2, a
platen 3 accommodated in the inside of the casing 2, four ink-jet
head 4, two conveyance rollers 5 and 6, a controller 7, etc.
The recording paper 100 is place on the upper surface of the platen
3. The four ink-jet heads 4 are arranged side by side in the
conveyance direction at a location above the platen 3. Each of the
ink-jet heads 4 is a so-called line type head having a plurality of
nozzles 15 (see FIG. 2) which are arranged side by side in the
width direction of the recording paper. In each of the ink-jet
heads 4, ink is supplied from a non-illustrated ink tank. Note that
inks of four different colors are supplied to the four ink jet
heads, respectively. Namely, the four ink jet heads 4 jet the
mutually different color inks, respectively.
As depicted in FIG. 1, the two conveyance rollers 5 and 6 are
arranged respectively on the rear and front sides with respect to
the platen 3. The two conveyance rollers 5 and 6 are driven by
non-illustrated motors, respectively, and convey the recording
paper 100 on the platen 3 in the front direction.
The controller 7 is provided with a CPU (Central Processing Unit),
a ROM (Read Only Memory), a RAM (Random Access Memory) and ASIC
(Application Specific Integrated Circuit) including a various kinds
of control circuits. Further, the controller 7 is connected
data-communicatively to an external apparatus 9 such as a PC, and
is configured to control various parts or elements of the printer 1
based on a print data transmitted from the external apparatus
9.
More specifically, the controller 7 controls the motors driving the
two conveyance rollers 5 and 6 so as to allow the two conveyance
rollers 5 and 6 to convey the recording paper 100 in the conveyance
direction. Further, while doing so, the controller 7 controls the
four ink-jet heads 4 to cause the ink jet heads 4 to jet the inks
towards the recording paper 100. By doing so, an image, etc., is
printed on the recording paper 100.
<Detailed Configuration of Ink-Jet Head>
Next, the ink jet heads 4 will be explained in detail. As depicted
in FIG. 2, each of the ink-jets 4 is provided with four head units
11 which are attached to a unit holding plate 10 in a state that
the four head units 11 are arranged side by side in the left/right
direction. Each of the four head units 11 is connected to a common
ink tank (not depicted in the drawings) via an ink supply hole 23
(see FIG. 3) which is formed in a holder 14 (to be described later
on). Namely, the respective four head units 11 jet a same color
ink.
As depicted in FIGS. 3 to 5, each of the head units 11 is provided
with six nozzle chips 12, a fixing plate 13, and a holder 14. Each
of the nozzle chips 12 has a planar shape that is rectangular, and
the plurality of nozzles 15 are aligned (in a row) on the lower
surface of each of the nozzle chip 12, along the longitudinal
direction thereof. Namely, the lower surface of each of the nozzle
chips 12 is a jetting surface 16 in which the ink is jetted from
the plurality of nozzles 15.
Here, provided that the ink-jet head 4 were a general line head,
each of the nozzle chips 12 is arranged such that the longitudinal
direction thereof is parallel to the width direction of the
recording paper. In contrast, in the embodiment, each of the nozzle
chips 12 is arranged such that the longitudinal direction thereof
crosses (intersects) the left/right direction as the width
direction of the recording paper and crosses the front/rear
direction as the conveyance direction, namely to assume an oblique
posture. The six nozzle chips 12 each of which is arranged in the
oblique posture are arranged side by side in the left/right
direction. Among two nozzle chips 12, among the six nozzle chips
12, which are adjacent in the left/right direction in each of the
head units 11, a part or portion of the nozzles 15 are overlapped
in the conveyance direction. As depicted in FIG. 3, a central
portion in the longitudinal direction of each of the nozzle chips
12 is formed with a supply port 17 communicating with an ink supply
hole of the holder 14 (to be described later on).
An inclination angle .theta. of each of the nozzle chips 12 with
respect to the left/right direction is not particularly limited.
However, as the angle .theta. is made greater, the arrangement
spacing distance between the nozzles 15 in the left/right direction
becomes smaller, thereby making it possible to increase the
resolution of the head 4. As depicted in FIG. 4, a case is assumed
wherein the arrangement pitch (alignment pitch) of the nozzles 15
in the longitudinal direction of chip (chip longitudinal direction)
of each of the nozzle chips 15 is made to be "P"; under a condition
that the angle .theta. is, for example, 60 degrees, the arrangement
pitch (alignment pitch) of the nozzles 15 in the width direction of
the recording paper becomes "P/2". Conversely, as the angle .theta.
is made smaller, although the arrangement spacing distance between
the nozzles 15 in the left/right direction becomes greater (thereby
reducing the resolution of the head 4), this makes it possible to
increase the width (overlapping width W1) of a portion at which
nozzles 15 overlap with each other between adjacent nozzle chips 12
in the conveyance direction. Note that in a case that the
above-described overlapping width W1 is small, the unevenness
(irregularity) in density of an image formed by nozzles 15 which
are overlapped in the conveyance direction tends to be conspicuous.
Due to this, the overlapping width W1 is preferably large in view
of improving the image quality.
Note that each of the nozzle chips 12 has a rectangular planar
shape, and an end surface 12a of an end portion, of each of the
nozzle chips 12, in the chip longitudinal direction of the nozzle
chip 12 is parallel to a direction (short direction of the chip;
chip short direction) which is orthogonal to the chip longitudinal
direction. The nozzle chip 12 having the above-described
rectangular shape is easily usable for an ink jet head of another
system, and has a high versatility. For example, by arranging the
nozzle chips 12 of the embodiment such that the chip longitudinal
direction is parallel to the conveyance direction of the recording
paper, it is possible to construct an ink jet head of the so-called
serial type which jets an ink while the ink-jet head is allowed to
move in the width direction of the recording paper. In this
situation, in a case that the planar shape of each of the nozzle
chips 12 is rectangular, namely, is such a shape that the end
surface 12a of the chip longitudinal direction is parallel to the
chip short direction, it is possible to make the size in the
conveyance direction of the ink jet head of the serial type to be
small.
As depicted in FIG. 2, also between two nozzle chips 12 belonging
to two adjacent head units 11, respectively, a part of the nozzles
15 are overlapped with each other in the conveyance direction. By
arranging the nozzles 15 each constructing one of the four head
units 11 to be joined (linked) with each other in the width
direction of the recording paper, a head of the line type is
realized. Note that in the present embodiment, the overlapping
width W1 of the nozzles 15 between two nozzle chips 12 in each of
the head units 11 (hereinafter referred to as "one head unit 11, as
appropriate), and an overlapping width W2 of the nozzles 15 between
two nozzle chips 12 belonging to adjacent two head units 11,
respectively, are made to be same. For example, provided that the
overlapping width W1=W2=4.2225 mm. Further, provided that the
inclination angle .theta. of the nozzle chip 12 is 60 degrees; and
that the arrangement pitch (alignment pitch) P of the nozzles 15 in
the chip longitudinal direction is 84.7 .mu.m (300 dpi), then the
arrangement pitch (alignment pitch) P of the nozzles 15 in the
paper width direction becomes P/2=42.35 .mu.m. In this case, since
the number of nozzles 15 included in the overlapping width W1 (W2)
is W1/(P/2), namely, is approximately 100 pieces. Consequently,
about 1/4 of all the nozzles 15 of each of the nozzle chips 12
overlap with one another.
The fixing plate 13 is a plate member formed of a metal, etc. The
fixing plate 13 is arranged at a location below the six nozzle
chips 12, namely, arranged on the side facing the jetting surfaces
16 of the nozzle chips 12. The fixing plate 13 is formed with six
holes 13a each of which is configured to expose the jetting surface
16a of one of the six nozzle chips 12. As depicted in FIG. 6B, each
of the nozzle chips 12 is joined, with an adhesive 18, to a
surrounding area of one of the holes 13a corresponding thereto and
formed in the upper surface of the fixing plate 13. Note that the
six holes 13a are formed by the punching processing. During the
punching processing, since the edge portion of each of the holes
13a is deformed to a small extent, the flatness (planeness) of the
lower surface of the fixing plate 13 becomes great. Note that the
term "flatness" is an index indicating the extent of deviation from
an ideal flat surface, and as the flatness of a surface as the
object is smaller, the object surface approaches closely to the
ideal flat surface. The increase in (degradation of) the flatness
due to the punching processing is corrected by projections 31 and
32 formed in the holder 14, as will be described next.
The holder 14 is produced, for example, by injection molding using
a synthetic resin material. The holder 14 is arranged to cover the
six nozzle chips 12 from thereabove, and holds the six nozzle chips
12. As depicted in FIGS. 3 to 5, the holder 14 has a ceiling
portion 20, two first walls 21 extending downward from the ceiling
portion 20, and five second walls 22 similarly extending downward
from the ceiling portion 20.
The ceiling portion 20 is arranged so as to overlap with the six
nozzle chips 12 in the up/down direction. The ceiling portion 20 is
formed with one ink supply hole 23. As depicted in FIG. 6B, the
inner surface of the ceiling 20 is joined to the upper surfaces of
the nozzle chips 12, with an adhesive 24. Although omitted in the
drawings, an ink flow channel connected to the ink supply hole 23
is formed in the inside of the ceiling portion 20. The ink flow
channel 23 is communicated with supply ports 17 of the six nozzle
chips 12. The ink supplied from the non-illustrated ink tank to the
ink supply hole 23 of each of the head units 11 is distributed to
the supply holes 17 of the six nozzle chips 12 by the ink flow
channel formed inside the ceiling portion 20. Namely, the nozzles
15 of the six nozzle chips 12 jet a same kind of ink.
The two first walls 21 extend downward respectively from both end
portions in the front/rear direction of the ceiling portion 20, and
cover the end surfaces 12a in the chip longitudinal direction of
the six nozzle chips 12 from the front/rear direction. Note that as
depicted in FIGS. 3 and 6B, any wall is not provided on both end
portions in the left/right direction of the ceiling portion 20,
thus allowing nozzle chips 12, included in the six nozzle chips 12,
which are located at the both ends in the left/right direction to
be exposed from the holder 14 in the left/right direction. Namely,
both the left and right end portions of the holder 14 are open
(released).
As described above, the direction of the end surface 12a of the end
portion in the longitudinal direction of each of the nozzle chips
12 is orthogonal to the chip longitudinal direction. Namely, the
end surface 12a is a surface crossing both of the front/rear
direction and the left/right direction. On the other hand, each of
portions on the inner sides in the front/rear direction of the
first walls 21 is formed with six recesses 21a each having an
inclined surface corresponding to the end surface 12a of one of the
six nozzle chips 12, and the end portions of the nozzle chips 12
are inserted into the recesses 21a, respectively. Namely, the first
walls 21 are arranged both on the front and rear sides,
respectively, of the six nozzle chips 12 so as to sandwich the six
nozzle chips 12 therebetween in the front/rear direction. Rear-side
portions 21b (rear interposed portions 21b), of one of the two
first walls 21 which is arranged on the front side of the six
nozzle chips 12, are arranged to be interposed into a location
between front end portions of adjacent nozzle chips 12 among the
six nozzle chips 12. Similarly, front-side portions 21b (front
interposed portions 21b), of the other of the two first walls 21
which is arranged on the rear side of the six nozzle chips 12, are
arranged to be interposed into locations between rear end portions
of adjacent nozzle chips 12 among the six nozzle chips 12.
As depicted in FIG. 5 and FIG. 6A, the lower surface of each of the
first walls 21 has five first projections 31 which are formed in
the lower surface with a spacing distance therebetween in the
left/right direction. Each of the first projections 31 has, for
example, a hemispherical outer shape and is formed integrally with
the first wall 21 by the molding. Further, each of the first
projections 31 has a portion thereof which is arranged in the
interposed portion 21a, of each of the first walls 21, arranged to
be interposed into the location between the end portions of the two
nozzle chips 12. As depicted in FIG. 6A, the lower surface of each
of the first walls 21 is joined to the fixing plate 13 with the
adhesive 24 in a state that the five first projections 31 are
pressed against and make contact with the upper surface of the
fixing plate 13.
Each of the second walls 22 is arranged between two nozzle chips
12, among the six nozzle chips 12, which are adjacent in the
left/right direction, and extends along the nozzle chips 12 in the
longitudinal direction of the nozzle chips 12. The lower surface of
each of the second walls 22 has a plurality of second projections
32 which are formed in the lower surface with a spacing distance
therebetween in the chip longitudinal direction. Similarly to the
first projections 31 as described above, each of these second
projections 32 also has a hemispherical outer shape and is formed
integrally with the second wall 22 by the molding. Note that,
however, the size (dimension) of the first projection 31 is greater
than the size of the second projection 32, as depicted in FIG. 5
and FIGS. 6A and 6B. Specifically, the diameter of the first
projections 31 is 0.6 mm, and the diameter of the second
projections 32 is 0.3 mm.
Further, the shapes of the first and second projections 31 and 32
are not limited to the above-described hemispherical shape. In view
of joining (adhesion) to the fixing plate 13, the first and second
projections 31 and 32 preferably have a shape having a flat surface
on an end portion thereof, such as a columnar shape, a truncated
conical shape, etc.
Furthermore, there are five gaps in total that are present among
the six nozzle chips 12. The second walls 22 are arranged in all
the five gaps, and the second projections 32 are formed in all of
the five second walls 22. In this configuration, regarding four
nozzle chips 12 which are included in the six nozzle chips 12 and
which are located on the central side in the left/right direction,
two pieces of the second walls 22 are consequently arranged on both
sides in the left/right direction with respect to each of the four
nozzle chips 12 on the central side. In addition, in this
configuration, the second projections 32 of a second wall 22
located on one side with respect to a certain nozzle chips 12,
among the four nozzle chips 12 on the central side, and the second
projections 32 of another second wall 22 located on the other side
with respect to the certain nozzle chip 12 are arranged to face one
another in the chip short direction, with the certain nozzle chip
12 sandwiched therebetween. Namely, one of the second projection 32
located on one side with respect to the certain nozzle chip 12 and
another one of the second projection 32 located on the other side
with respect to the certain nozzle chip 12 are arranged on a same
line L (see FIG. 5) that is parallel to the chip short
direction.
As described above, the first projections 31 and the second
projections 32 are formed at a time during the molding of the
holder 14. Here, in the injection molding of the holder 14, it is
difficult to uniformize the height position highly precisely over
the entire area of the lower surface of the holder 14, due to any
factor such as any expansion and contraction (shrinkage) of the
resin material. In contract, the configuration provided with the
plurality of first projection 31 and the plurality of second
projections 32 in the lower surface of the holder 14, it is
possible to uniformize the height position of the fixing plate 13
by appropriately adjusting the heights of the projections 31 and/or
32. Note that the adjustment of the heights of the projections 31
and/or 32 can be performed by adjusting a metallic mold used for
the injection molding with an adjusting member such as screw, etc.
In such a manner, by adopting the configuration for allowing each
of the plurality of projections 31 and 32 formed in the lower
surface of the holder 14 to make contact with the fixing plate 13,
it is possible to suppress the flatness of the fixing plate 13 to
be small, as compared with a case of allowing the entire area of
the lower surface of the holder 14 to make direct contact with the
fixing late 13.
As depicted in FIG. 6B the lower surface of each of the second
walls 22 is joined to the fixing plate 13 by the adhesive 24 in a
state that the plurality of second projections 32 are pressed
against and making contact with the upper surface of the fixing
plate 13.
As explained above, in each of the head units 11 of the embodiment,
the two first walls 21 of the holder 14 are arranged on the outer
sides in the front/rear direction with respect to the six nozzle
chips 12, respectively. The five first projections 31 are formed in
each of the two first walls 21, and the first walls 21 are joined
to the fixing plate 13 in the state that the five first projections
31 of each of the first walls 21 are making contact with the fixing
plate 13. Owing to this configuration, it is possible to realize a
highly precise flatness of the fixing plate 13 in each of the head
units 11, and to suppress any variation (fluctuation) in the
heights of the fixing plates 13 among the four head units 11, as
well.
On the other hand, there are not any walls on the outer sides in
the left/right direction with respect to the six nozzle chips 12,
and the nozzle chips 12, among the six nozzle chips 12, located on
the both end sides in the left/right direction are exposed from the
holder 14. The phrase that the "nozzle chips 12 are exposed from
the holder 14" means a situation wherein nozzle chips 12 on the
both ends in the left/right directions are not covered by the
holder 14. In this configuration, in a case that the four head
units 11 are arranged side by side in the left/right direction, it
is possible to arrange nozzle chips 12, of two adjacent heads units
11 among the four head units 11, closely to each other, thereby
making it possible to shorten the distance between the nozzle chips
12 belonging respectively to the two adjacent head units 11.
A portion of each of the first walls 21 is allowed to interpose
(enter) into the location between two adjacent nozzle chips 12
among the six nozzle chips 12. This configuration can be considered
also as a configuration wherein the six recesses 21a corresponding
to the six nozzle chips 12, respectively, are formed in a portion
on the inner side in the front/rear direction with respect to the
first walls 21. In this configuration, the nozzle chips 12 can be
easily positioned with respect to the first walls 21 by inserting
the respective nozzle chips 12 into the recesses 21a, respectively,
during the assembly.
Further, each of the first projections 31 has a portion thereof
which is arranged in the interposed portion 21a, of each of the
first walls 21, arranged to be interposed into the location between
the end portions of adjacent nozzle chips 12. With this, the
distance between the first projections 31 and the nozzle chips 12
can be made small, thereby making it possible to determine the
height position of the fixing plate 13 in the vicinity of the
nozzle chips 12.
Furthermore, in the embodiment, each of the second walls 22 of the
holder 14 are arranged between two adjacent nozzle chips 12, among
the six nozzle chips 12, which are adjacent in the left/right
direction. Each of the second walls 22 is formed with the plurality
of second projections 32, and the plurality of second walls 22 are
joined to the fixing plate 13 in the state that the plurality of
second projections 32 are making contact with the fixing plate 13.
Owing to this configuration, the height position of the fixing
plate 13 can be determined assuredly also between the nozzle chips
12.
Note that since each of the second walls 22 is arranged between
nozzle chips adjacent in the left/right direction, the spacing
distance between the two adjacent nozzle chips 12 becomes great
owing to the presence of the second wall 22. As the spacing
distance is greater, the overlapping width W1 of the nozzles 15
between the two adjacent nozzle chips 12 becomes smaller, which in
turn further makes it even difficult to allow the nozzles 15 to be
continued to each other in the two adjacent nozzle chips 12. In
view of this, in the present embodiment, all the six nozzle chips
12 of one head unit 11 are configured to jet the same kind of ink.
In such a case, even if the two nozzle chips 12 are apart from each
other to some extent in the left/right direction, it is not
particularly difficult to allow the nozzles 15 configured to jet a
same color ink to overlap with each other. Conversely, the
configuration can be considered as a configuration wherein the
second walls 22 can be easily arranged between the two adjacent
nozzle chips 12.
Although it is allowable to form the first and second projections
31 to 32 to have a same size (dimension), the width of the second
walls 22 cannot be made to be much great in view of securing the
above-described overlapping width W1 to not less than a
predetermined extent. Accordingly, there is a limit for increasing
the size of the second projections 32, as well. On the other hand,
there is no such a limitation regarding the first walls 21
positioned at the outer side in the front/rear direction with
respect to the nozzle chips 12. Thus, in the present embodiment,
the first projections 31 formed in the first walls 21 are formed to
be greater than the second projections 32 formed in the second
walls 22.
Further, in the embodiment, the second walls 22 each formed with
the second projections 32 are arranged in all the five locations
between the six nozzle chips 12. With this, it is possible to more
assuredly suppress any variation in the height of the fixing plate
13 in the plane direction of the fixing plate 13.
With respect to the nozzle chips 12 on the central side, two pieces
of the second wall 22 are arranged on the both sides in the
left/right direction with respect to each of the nozzle chips 12 on
the central side. In addition, each of the second projections 32
located on one side with respect to a certain nozzle chips 12,
among the nozzle chips 12 on the central side, and one of the
second projections 32 located on the other side with respect to the
certain nozzle chip 12 are arranged to face each other in the chip
short direction, with the certain nozzle chip 12 sandwiched
therebetween. With this, the pressing manner by which the second
projections 32 press the fixing plate 13 on the both sides in the
chip short direction of the nozzle chips 12 becomes uniform,
thereby making it possible to reduce the variation in height of the
fixing plate 13 to be small.
In the embodiment as described above, the ink jet head 4
corresponds to the "liquid jetting apparatus" of the present
teaching. The width direction of the recording paper corresponds to
the "first direction" of the present teaching, and the conveying
direction corresponds to the "second direction" of the present
teaching. The chip longitudinal direction corresponds to the
"predetermined direction" of the present teaching, and the chip
short direction corresponds to the "direction orthogonal to the
predetermined direction" of the present teaching.
Next, an explanation will be given about modifications in which
various changes are made to the above-described embodiment. Note
that, however, any parts or components constructed in the similar
manner to that in the above-described embodiment are designated
with same reference numerals, and description thereof is omitted as
appropriate.
[Modification 1]
It is allowable that, as in a head unit 11A depicted in FIG. 7, two
projections 31A are arranged to face each other in the chip
longitudinal direction such that each of the nozzle chips 12 is
sandwiched therebetween. With this, the pressing manner by which
the first projections 31 press the fixing plate 13 becomes uniform
on the both sides in the chip longitudinal direction, thereby
making it possible to reduce the variation in height of the fixing
plate 13 to be small. Further, as depicted in FIG. 7, in a case
that the two first projections 31A are arranged on a straight line
extending in the chip longitudinal direction and passing through
the plurality of nozzles 15, it is possible to reduce the variation
in height of the fixing plate 13 on the both sides in the chip
longitudinal direction to be further small.
[Modification 2]
In the embodiment, two pieces of the second projection 32 arranged
on the both sides of a nozzle chip 12 face each other in the chip
short direction. It is allowable, however, that two pieces of
second projections 32B on the both sides of each of the nozzle
chips 12 face each other in the left/right direction, as in a head
unit 11B depicted in FIG. 8. Namely, it is allowable that the
positions of two second projections 32B, which are arranged on both
the left and right sides of one piece of the nozzle chips 12, are
coincident in the front/rear direction.
[Modification 3]
It is allowable that two or more pieces of a first projection 31C
may be arranged along each of end surfaces 12a of the end portions
in the longitudinal direction of each of the nozzle chips 12, as in
a head unit 11C depicted in FIG. 9. In this configuration, it is
possible to determine the height position of the fixing plate 13
assuredly in the vicinity of the end surfaces 12a of each of the
nozzle chip 12.
[Modification 4]
In the embodiment, the second walls 22 are arranged in all of the
five gaps between the six nozzle chips 12. In this configuration,
however, the number of the second projection 32 becomes great. As
the number of the second projection 32 increases, it takes more
labor and effort for adjusting the heights of the second
projections 32 so as to suppress the flatness of the fixing plate
13 to be small. In view of this, it is allowable that the second
walls may be arranged only at a portion of the locations between
the six nozzle chips 12. By omitting a portion of the second walls,
such an effect is obtained that the overlapping amount of the
nozzles 15 can be great at a location or locations at which the
second wall is omitted.
Note that no wall is present at the both sides in the left/right
direction of the six nozzle chips 12, and there is also no
projections for determining the height position of the fixing plate
13. In view of this, in a case of arranging the second walls only
at a portion of the locations between the six nozzle chips 12, it
is preferred that second walls 22D are arranged such that each of
the second walls 22D is arranged between two adjacent nozzle chips
12, among the six nozzle chips 12, which are arranged closer to one
end side or the other end side in the left/right direction, as in a
head unit 11D depicted in FIG. 10A. In a case of arranging more
pieces of the second wall, it is preferred that second walls 22E
are arranged also between two nozzle chips 12, among the six nozzle
chips 12, which are arranged on the central side in the left/right
direction, in addition to the above-described two second walls 22D
each arranged closer to one end side or the other end side in the
left/right direction, as in a head unit 11E depicted in FIG. 10B.
With such a configuration, it is possible to determine the height
position of the fixing plate 13 assuredly also at the central
portion thereof which is distanced from the both end portions in
the left/right direction.
[Modification 5]
It is not necessarily indispensable that the second projections are
formed at all of the second walls each of which is located between
adjacent nozzle chips among the six nozzle chips. Namely, in a head
unit 11F depicted in FIG. 11, second projections 32F are provided
only on three second walls 22F, in total, which are included in
five second walls 22F present between the six nozzle chips 12, and
which are located at the both end sides and the central side in the
left/right direction. In this configuration, since the number of
the second projection 31F is smaller as compared with the
configuration of the embodiment (see FIG. 5), it is possible to
reduce the labor and effort for performing the adjustment for the
second projections 31F.
[Modification 6]
It is not necessarily indispensable that the size (dimension)
and/or the density of arrangement of the second projections are
same among the plurality of second walls arranged side by side in
the width direction of the recording paper. As described above, at
the both sides in the left/right direction of the six nozzle chip
12, there are no walls and there are also no projections for
determining the height position of the fixing plate. In this
situation, in view of suppressing the variation in the height of
the fixing plate at the end sides in the left/right direction, it
is preferred that the second projections formed on the second
walls, which are located at the endmost sides in the left/right
direction are allowed to substitute for projections which might be
originally provided on the wall portions that might be originally
located at the outer sides of the six nozzle chips with respect to
the left/right direction.
From the above viewpoint, it is preferred that in each of the
second walls arranged on one end side or the other end side in the
left/right direction, the size of the second projections and/or the
arrangement density of the second projections are/is greater than
those of the second projections of the second walls arranged on the
central side. For example, in a head unit 11G depicted in FIG. 12A,
second projections 32Ga formed in two second walls 22Ga arranged on
the both end sides in the left/right direction are greater than
second projection 32Gb formed in three second walls 22Gb located on
the central side in the left/right direction. Alternatively, in a
head unit 11H depicted in FIG. 12B, each of two second walls 22Ha
located respectively on the both end sides in the left/right
direction has such a configuration wherein the arrangement pitch of
second projections 32H is smaller and the arrangement density of
the second projections 32H is higher than the arrangement pitch and
the arrangement density of the second projections 32H of three
second walls 22Hb arranged on the central side. In the
configuration depicted in FIG. 12B, in a case that the arrangement
pitch of the second projections 32H is too narrow, the number of
the second projections 32H becomes too great, which in turn
requires more labor and effort for the adjustment. Further, in a
case that the arrangement pitch of the second projections 32H is
too great, it is not possible to suppress the flatness of the
fixing plate 13 to be small. An example of the appropriate
arrangement pitch of the second projections 32H includes, for
example, 2.35 mm for those arranged on the second walls 22Ha on the
both end sides in the left/right direction, and 5.5 mm for those
arranged on the second walls 22Hb on the central side.
[Modification 7]
It is not necessarily indispensable that the second projections are
arranged evenly (uniformly) in the chip longitudinal direction. For
example, since the first projections are arranged in the vicinity
of the end portions of the second walls, it is allowable that the
second projections are arranged in a concentrated manner at a
central portion of each of the second walls. Specifically, in a
head unit 11I depicted in FIG. 13A, second projections 32I are
arranged only at a central portion of each of the second walls
22.
Alternatively, in a head unit 11J depicted in FIG. 13B, the size of
second projections 32Ja arranged on a central portion of each of
the second walls 22 is greater than the size of second projections
32Jb arranged on end sides of each of the second walls 22. Note
that in the configuration depicted in FIG. 13B, in a case that the
width of the second walls 22 is made to be too large, the
overlapping width between the nozzle chips 12 becomes small. On the
other hand, in a case that the width of the second walls 22 is made
to be too small, it is only possible to form second projections
having a small size. In view of these situations, the appropriate
range of the width of the second walls 22 is in a range of 0.5 mm
to 0.6 mm. In this case, the diameter of the second projections
32Jb on the end sides is preferably made to be 0.3 mm, and the
diameter of the second projections 32Ja on the central side is
preferably made to 0.45 mm that is 1.5 times the diameter of the
second projections 32Jb on the end sides.
Alternatively, in a head unit 11K depicted in FIG. 13C, the
arrangement pitch of second projections 32K is smaller and the
arrangement density of the second projections 32K is higher in the
central portion of each of the second walls 22 than in those in the
end portions thereof.
In the configurations depicted in FIGS. 13A to 13C, respectively,
it is possible to suppress the flatness of the fixing plate 13 to
be small at the central portion thereof distanced from the first
projections, by making the number of the second projections to be
great at the central portion of each of the second walls, or by
making the size of the second projections to be large at the
central portion of each of the second walls. Further, in
particular, in the configurations depicted in FIGS. 13A and 13C, it
is possible to reduce the labor and effort required for the
adjustment by making the number of the second projections to be
small at a location close or near to the first projection.
[Modification 8]
It is allowable that an end surface 12La of end surfaces 12La of
end portions in the chip longitudinal direction of each of nozzle
chips 12L may be a surface along the left/right direction, as in a
head unit 11L depicted in FIG. 14. In a case that the end surface
12La of the nozzle chip 22L is along the left/right direction, an
end portion of the nozzle chip 12L is made to abut against a same
inner wall surface of a holder 14L, and thus the positions of the
nozzle chips 12L in the conveyance direction can be easily
aligned.
[Modification 9]
It is also possible to adopt such a configuration that no walls are
provided between nozzle chips 12M, as in a head unit 11M depicted
in FIG. 15. In the configuration of FIG. 15, two first walls 21M of
a holder 14M are arranged at the outer sides, respectively, in the
front/rear direction with respect to six nozzle chips 12M. The
lower surface of each of the first walls 21M is formed with six
first projections 31M. In this configuration also, it is possible
to realize a highly precise flatness for the fixing plate by
joining the first walls 21M to the fixing plate in a state that the
first projections 31M are making contact with the fixing plate.
Note that the configuration of FIG. 15 is suitable for a case that
one piece of the nozzle chips 12M jets two or more kinds of the
ink. For example, in the configuration of FIG. 15, nozzles 15Ma,
which are included in a plurality of nozzles 15M constructing each
of the nozzle chips 12M and which are located on the front side,
are nozzles configured to jet a black ink; and nozzles 15Mb located
on the rear side are nozzles configured to jet a yellow ink. In
this case, the length of a nozzle row jetting one color ink is
half, and thus unless the distance between two pieces of the nozzle
chip 12M is considerably short, it is not possible, in two pieces
of the nozzle chip 12M, to make nozzles jetting the same color ink
to be continuous and/or to overlap the nozzles jetting the same
color ink. Accordingly, in a case of using the nozzle chips 12M
configured to jet two or more color inks as depicted in FIG. 15, it
is preferred to adopt a configuration wherein no walls are present
between two pieces of the nozzle chip 12M and that two pieces of
the nozzle chip 12M are arranged side by side in the left/right
direction without any walls intervened therebetween.
As described above, the length of the nozzle row jetting one color
ink is half in the configuration of Modification 9 as compared with
the configuration of the embodiment (see FIG. 5). Accordingly, the
overlapping width W1 between two adjacent nozzle chips 12M becomes
small, and thus it is difficult to make the number of the
overlapping nozzles 15 to be equal (equivalent) to that in the
configuration of the embodiment (see FIG. 5). Even under this
situation, however, it is desired that the number of the nozzle 15M
jetting a same color ink and overlapping between the two adjacent
nozzle chips 12 M is secured to some extent (for example, 40
pieces), for the purpose of making the joint between two adjacent
nozzle chips 12 be less conspicuous.
Regarding this task, in FIG. 15, the overlapping width W1 (=2.111
mm) and the total number (200 pieces) of the nozzles 15 in each
nozzle row jetting one of the respective color inks are made to be
half of those in the above-described embodiment. On the other hand,
the arrangement pitch (84.7 .mu.m) of the nozzles 15M in the chip
longitudinal direction and the inclination angle (60 degrees) of
the nozzle chip 12M with respect to the left/right direction are
made to be same as those in the above-described embodiment. In such
a case, the number of the nozzles 15M which are configured to jet a
same color ink and which are overlapped with each other between two
adjacent nozzle chips 12M is approximately 50 pieces, namely, 1/4
of the nozzles jetting the same color ink in each of the head chips
12M overlap with each other.
Note that in the nozzle chip 12M of FIG. 15, the black nozzles 15Ma
located on the front side correspond to the "first nozzles" of the
present teaching, and the yellow nozzles 15Mb located on the rear
side correspond to the "second nozzles" of the present
teaching.
Further, as a modification of the configuration of FIG. 15, it is
allowable that, as in a head unit 11N of FIG. 16, one piece of
nozzle chip 12N is configured to have two nozzle rows. The
configuration of FIG. 16 is similar to that in FIG. 15 in that the
kinds of the ink jetted are different on one side and the other
side in the chip longitudinal direction of two nozzle rows. Note
that, however, in the configuration of FIG. 16, two nozzle chips
12Na configured to jet black and yellow inks and two nozzle chips
12Nb configured to jet cyan and magenta inks are arranged
alternately in the width direction of the recording paper. Namely,
between the two nozzle chips 12Na, one of another nozzle chips 12Nb
jetting the inks different from those jetted from the two nozzle
chips 12Na is arranged. In this configuration, since four color
inks can be jetted from one head unit, it is possible to construct
a color ink jet printer of which size in the conveyance direction
is smaller as compared with a configuration wherein four color ink
jet heads are arranged side by side in the conveyance direction.
Further, as a modification of FIG. 16, it is allowable that as in a
head unit 11O depicted in FIG. 17, the colors of the inks jetted
from two nozzle rows which are included in one nozzle chip 12O may
be different. Specifically, in a nozzle row which is included in a
certain nozzle chip 12O and which is located on the left side,
nozzles 15O on the front side jet a cyan ink, and nozzles 15O on
the rear side jet a magenta ink. On the other hand, in a nozzle row
which is included in the certain nozzle chip 12O and which is
located on the right side, nozzles 15O on the front side jet a
black ink and nozzles 15O on the rear side jet a yellow ink.
Namely, the four color inks may be jetted from one nozzle chip
12O.
[Modification 10]
In the embodiment, the holder 14 of each of the head units 11 has
the two first walls 21 extending downwardly from both end portions
in the front/rear directions of the ceiling portion 20, and the
five second walls 22 extending downwardly from the ceiling portion
20. However, there is no limitation to this. For example, as
depicted in FIG. 18, the folder 14 may further have two third walls
25 extending downwardly from both the left and right end portions
of the ceiling portion 20. In such a case, the flatness of the
fixing plate 13 can be further enhanced.
[Modification 11]
In the embodiment, any projection is not provided on the lower
surface of the fixing plate 13. However, there is no limitation to
this. For example, as depicted in FIG. 19, the lower surface of the
fixing plate 13 may be provided with ribs 13b projecting downwardly
and extending in the chip longitudinal direction so as to prevent
the recording paper 100 from contacting the jetting surface 16. In
such a case, it is preferred that the ribs 13b projecting from the
lower surface of the fixing plate 13 and the second projections 32
of each of the second walls 22, which are fixed on the upper
surface of the fixing plate 13, are not overlapped with one another
in the up/down direction, namely are shifted in the left/right
direction relative to one another, so as to maintain the flatness
of the fixing plate 13.
[Modification 12]
In the above-described embodiment, the holder and the fixing plate
are provided individually (separately) on each of the head units.
Namely, the holder and the fixing plate are configured to be
separated among the plurality of head units. On the other hand, it
is allowable to provide such a configuration that the holder and
the fixing plate are each linked to each other among the plurality
of head units so as to be integrally formed.
[Modification 13]
In FIGS. 4 and 5 of the above-described embodiment, the edge
portions of the holder 14 in the conveyance direction are parallel
to the left/right direction. It is allowable, however, that the
edge portions are formed to have a zig-zag shape in accordance with
the shape of the end surfaces of the respective nozzle chips
12.
[Modification 14]
In FIG. 5 of the above-described embodiment, the both end portions
of each of the second walls 22 extending in the chip longitudinal
direction are continuously connected to the first walls 21. It is
allowable, however, that the second walls are not connected to the
first walls. It is sufficient, for example, that the second walls
22 are provided on locations such as those in the vicinity of an
end portion of the nozzle chip 12 and/or the central portion of the
nozzle chip 12 at which the second projections 32 are desired to be
arranged, and other than that, it is allowable that the second wall
22 are not present.
In the embodiment and the modifications thereof as described above,
the present teaching is applied to the ink jet head configured to
jet an ink(s) onto a recording paper to thereby record an image,
etc. on the recording paper. However, the present teaching is
applicable also to liquid jetting apparatuses usable for various
kinds of applications other than the printing of image, etc. For
example, the present teaching is applicable also to a liquid
jetting apparatus which forms a conductive pattern on a surface of
a substrate by jetting a conductive liquid onto the substrate.
* * * * *